JDBC连接数据库（MYSQL）工具类

JDBC连接数据库总共七步：

1，加载数据库驱动（如oracle，mysql...）；

2，提供JDBC连接的URL,USER,PASSWORD；

3，创建数据库连接；

4，创建Statement；

5，执行SQL语句；

6，处理结果；

7，关闭JDBC资源。


下面以MYSQL数据库为例！

注：别忘记加这个包！mysql-connector-java-5.0.8-bin.jar

以下是代码：


工具类：JDBCUtil.java （提供连接、关闭连接释放JDBC资源）
   
package collection.utils;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;
public class JDBCUtil {
    static{
        try {
            Class.forName("com.mysql.jdbc.Driver");
        } catch (ClassNotFoundException e) {
            e.printStackTrace();
        }
    }
    //获得连接
    public static Connection getConnection(){
        Connection conn = null;
        String url = "jdbc:mysql://localhost:3306/dbtest?useUnicode=true&characterEncoding=utf8";
        String user = "root";
        String password = "root";
        try {
            conn = DriverManager.getConnection(url, user, password);
            System.out.println("connection is successful!");
        } catch (SQLException e) {
            System.out.println("connection error！");
            e.printStackTrace();
        }
        return conn;
    }
    //释放JDBC资源（关闭顺序与声明时的顺序相反）
    public static void release(Connection conn,Statement state,ResultSet rs){
        if(rs != null){
            try {
                rs.close();
            } catch (SQLException e) {
                e.printStackTrace();
            }
        }
        if(state != null){
            try {
                state.close();
            } catch (SQLException e) {
                e.printStackTrace();
            }
        }
        if(conn != null){
            try {
                conn.close();
            } catch (SQLException e) {
                e.printStackTrace();
            }
        }
    }
}


测试类：DBTest.java (对数据进行增、删、改、查)
   
package collection.db.mysql;
import java.sql.Connection;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;
import org.junit.Test;
import collection.utils.JDBCUtil;
public class DBTest {
    private static Connection conn;
    private static Statement state;
    // 1，添加数据
    @Test
    public void insert() {
        conn = JDBCUtil.getConnection();
        try {
            String sql = "INSERT INTO users(id,username,age,job,address) VALUES(1,'花无缺',20,'武林大侠','云游天下，四海为家！')";
            state = conn.createStatement();
            int count = state.executeUpdate(sql);
            System.out.println("Operation is successful!");
            System.out.println("共插入了" + count + "条数据！");
            //操作后释放资源
            JDBCUtil.release(conn, state, null);
        } catch (SQLException e) {
            System.out.println("insert error!");
            e.printStackTrace();
        }
    }
    // 删除数据
    @Test
    public void delete() {
        conn = JDBCUtil.getConnection();
        try {
            String sql = "DELETE FROM users WHERE username='花无缺1'";
            state = conn.createStatement();
            int count = state.executeUpdate(sql);
            System.out.println("Operation is successful!");
            System.out.println("共删除了" + count + "条数据！");
            JDBCUtil.release(conn, state, null);
        } catch (SQLException e) {
            System.out.println("delete error!");
            e.printStackTrace();
        }
    }
                                         
    //修改数据
    @Test
    public void update(){
        conn = JDBCUtil.getConnection();
        try {
            String sql = "UPDATE users SET job = '天下第一' WHERE id = '1'";
            state = conn.createStatement();
            int count = state.executeUpdate(sql);
            System.out.println("Operation is successful!");
            System.out.println("共修改了" + count + "条数据！");
            JDBCUtil.release(conn, state, null);
        } catch (SQLException e) {
            System.out.println("update error!");
            e.printStackTrace();
        }
    }
                                         
    //查询数据
    @Test
    public void query(){
        conn = JDBCUtil.getConnection();
        try {
            String sql = "SELECT * FROM users";
            state = conn.createStatement();
            ResultSet rs = state.executeQuery(sql);
            System.out.println("Operation is successful!");
            System.out.println("查询的数据结果如下：");
            while(rs.next()){
                int id = rs.getInt("id");
                int age = rs.getInt("age");
                String username = rs.getString("username");
                String job = rs.getString("job");
                String address = rs.getString("address");
                System.out.println("工号:"+id+",姓名："+username+",年龄："+age+",职位："+job+",地址："+address);
            }
            JDBCUtil.release(conn, state, rs);
        } catch (SQLException e) {
            System.out.println("query error!");
            e.printStackTrace();
        }
    }
}